1. Field of the Invention
This invention relates generally to improvements in a noise attenuating device functioning under resonance, and more particularly to a resonator used in an exhaust system of an automotive internal combustion engine.
2. Description of the Prior Art
Automotive vehicles are equipped with a resonator in an exhaust system in order to attenuate exhaust noise under effect of resonance. Hitherto a variety of resonators have been proposed and put into practical use. One of them is constructed as follows: An exhaust gas introduction tube is disposed to pass through a main body of the resonator. A resonance chamber is defined within the main body. A tuning tube is connected at its one end with the exhaust gas introduction tube to establish communication of the inside of the introduction tube with the resonance chamber. With this arrangement, exhaust noise is attenuated under effect of a resonator arrangement including the resonance chamber and the tuning tube.
However, the following difficulties have been encountered in the above arranged resonator: The tuning tube is usually connected at its one end with the exhaust gas introduction tube, and therefore it is difficult to enlarge the inner diameter of the tuning tube over that of the exhaust gas introduction tube. This unavoidably suppresses the noise attenuating effect of the resonator, which has been confirmed by experiments. Additionally, such a cantilever-type support for the tuning tube causes stress to concentrate at the joint section of the tuning tube with the exhaust gas introduction tube. Accordingly, the tuning tube is liable to be broken.